Shortly after the events of Aliens, Ellen Ripley (Sigourney Weaver) crash-lands on a prison planet, along with an alien. The all-male prisoners, led by Dillon (Charles Dutton), have found religion and don’t want a female bringing temptation. She’s left with only the doctor (Charles Dance) to talk to, until the killings begin.
The first three Alien movies focus on one feeling, one emotion. For Alien, it is terror. For Aliens it is excitement, thrills. For Alien³, it is depression. All are successful in their ways, but while terror and excitement are prime ingredients for a good film, depression isn’t.
Alien³ attempts a return to the claustrophobic feeling Ridley Scott created in Alien, but instead manages desolation. Now it is possible to make an interesting bleak movie (though not an exciting one), but only when something is done with that gloom. All Alien³ can do is present it.
The story is similar (too similar) to the first film as a group of people find themselves confined with an alien. It kills, we watch. But none of those killings are visceral; none are frightening. They are all just sad. The religion of the ex-convicts could have been fascinating, but isn’t as director David Fincher and the multiple writers and editors don’t do anything with it. They pray and Dillon yells at “the bothers” when they misbehave, but that’s about it.
Fincher shoots with a green and gray pallet making every room and corridor look the same. A majority of the characters look the same as well, all dressing the same, with the same hair cut, and speaking with similar voices. Except for Ripley, Dillon, the doctor, and the leader, I can’t tell who is who. When someone dies, I don’t know who it is, so, I don’t care.
As a non-action film, interest could have been generated by character relationships, but Alien³ supplies only one relationship of any interest, and then kills off one of the people.
Suffering from a flaw of many sequels, Alien³ pretends that what is going on is new to the audience. It moves slowly, building up the tension and mystery, and it asks the audience to contemplate the questions: is there an alien on the planet, and if so, what is this alien like and what will it do? But we already know all of it. There is no mystery. As soon as the name of the film pops up, we know there is an alien, and what it’s going to do is kill.
Taking Alien³ as part of a continuing story with the two previous films, it is a horrendous conclusion, destroying a substantial section of what came before. Killing off Newt and Hicks, and leaving an impregnated and doomed Ripley makes everything in Cameron’s Aliens pointless. Competent storytelling would say to replace most of Aliens with a five-minute scene of Ripley going back to the planet with some nameless soldiers, and then another of her damaged ship floating away. Anything else needed (like the Marines losing) is mentioned in Alien³. Or just edit out reference to the marines, and have Ripley crash after a facehugger somehow entered her escape vehicle at the end of Alien. But then, Alien³ has nothing to offer to a longer story while Aliens does. I prefer to say the series ended with Ripley, Hicks, and Newt flying away (closer to what Scott or Cameron might say), or to go with the comic book storyline (which I only vaguely know, but it has to be better). So, instead of giving Alien³ a 
rating for mutilating the series, I take it on its own, as a single film with no relationship to the earlier movies. And as a standalone, it isn’t exciting, or interesting, but it still has a cool monster munching on screaming people and there’s entertainment in that.
The production problems of Alien³ have become famous, with Fincher walking out before editing. Some have claimed that since Fincher has proven his skill (with Fight Club), the problems must be the result of studio interference. A new “workprint” version, that is supposed to be closer to Fincher’s vision (who knows, Fincher won’t say) is available, and while it is better for being more coherent with a better flow, the major problems are still there. This is a melancholy retread, and nothing Fincher might have done would have changed that.